This invention is concerned with the attachment of windscreen wiper blades to wiper arms, in particular with the use of adaptors to allow side-mounting blades to be used with types of wiper arms not expressly intended to carry them.
A known type of side-mounting wiper blade includes a circumferentially grooved mounting pin, extending from a side of the blade, and lying in use approximately parallel to the windscreen being wiped. One example of such a wiper blade is shown in British Pat. No. 1,254,109.
The invention concerns adaptors to attach side mounting wiper blades of the type described above to wiper arms of "shepherd's crook" kind. One example of such an arm is shown in British Pat. No. 726,275. Such an arm has an outer portion formed of bar and comprising, in succession, a straight main part, a part curved into semi-circular shape, and a short straight terminal part, parallel to and spaced from the lower face of the main part.
"Shepherd's crook" arms are widely in use on existing cars in conjunction with wiper blades which are not of the side mounting kind. It is advantageous to a user of such a car to be able to replace an existing wiper blade by a side mounting blade because it is recognized that a side mounting blade gives a superior performance as compared with older kinds of blades. For example they provide a lower profile which results in less exposure to lifting by airflow when the car is traveling at high speeds and present a better appearance. However, present blades for "shepherd's crook" arms are equipped with a special arm-to-blade connector for retaining the blade on the "shepherd's crook" arm. There are, readily available for replacement, side mounting blades carrying a grooved pin which is accomodated by special arms which carry a receptor for the pin.
At present there is no universal adaptor for effecting interchangeability and compatability between "shepherd's crook" arms and side mounting blades. Although couplers and adaptors have been provided for attaching "shepherd's crook" type arms to side mounted blades the known couplers are either required to be permanently affixed to the pin or are retained by detent means which cooperate with corresponding latching means on the arm such as a shoulder or aperture.
An example of the permanently affixed type is shown in U.S. Pat. No. 3,843,994 issued Oct. 29, 1974. This coupler is designed for use with a blade having a latching receptor for a pin type arm-to-blade connector wherein the pin is secured to the arm. Alternatively it may be permanently attached to a laterally extending pin secured to the blade during manufacture. It is not intended for connecting a side mounting blade having a grooved mounting pin to a blade for side mounting on a "shepherd's crook" arm.
An example of an adaptor which is retained by cooperating detent means on the arm and blade is illustrated in U.S. Pat. No. 4,023,232 issued May 17, 1977, priority date May 31, 1975. This adaptor is dependent on the shape of the hook end of the arm as well as the location and shape of the piercing in the arm.